Implicações do consumo de cafeína sobre a pressão arterial de repouso / Implications of caffeine consumption and resting blood pressure

Objetivo: O objetivo do presente estudo foi revisar a literatura sobre o comportamento na PA de repouso decorrente da ingestão crônica de cafeína, relacionando tal comportamento com possíveis mecanismos fisiológicos. Métodos: Foram realizadas buscas de artigos originais em inglês nas bases de dados Medline, Lilacs e SciELO até novembro de 2009, utilizando os termos caffeine, blood pressure, heart rate, chronic effect e cardiovascular response. Resultados: De um total de 564 estudos, apenas 29 compuseram a presente revisão. Vários estudos não observaram aumento da PA em humanos (normotensos e hipertensos) ou ratos (normotensos). Entretanto, em ratos hipertensos, os resultados dos estudos convergiram para o aumento da PA de repouso. Conclusão: Mesmo com certas lacunas em relação aos possíveis mecanismos fisiológicos envolvidos nos ajustes cardiovasculares relacionados à cafeína, nossa conclusão sugere que pessoas com hipertensão arterial sistêmica tenham cautela quanto ao uso diário dessa substância...

Exercise protects rat testis from cyclophosphamide-induced damage / O exercício físico protege o testículo de ratos de lesões teciduais induzidas por ciclofosfamida

To investigate the effect of chronic moderate exercise on male reproductive tract of Wistar rats submitted to a single dose of cyclophosphamide (CP). Animals were submitted to swimming exercise during 21 days or maintained at sedentary state. Trained (TCP) and sedentary (SCP) groups received a single dose of CP (200 mg kg-1, i.p.). Trained (TCo) and sedentary (SCo) control animals received sterile PBS. Animals were killed after one week and testis, epidydimis and seminal vesicle contend were weighted. Testis were embebbed in parafim and stained with hemotaxilin and eosin. Fifty seminiferous tubules of each animal were analyzed by Johnsen score. Mean Sertoli cells counts per tubule and Leydig cells counts per area were evaluated. CP treatment impairs body weight gain in trained and sedentary animals. Liver and seminal vesicle contend were reduced only in SCo group. SCP animals presented decreased Johnsen scores, indicating a slight toxicity over germinative cells, whereas trained (TCo and TCP) animals presented increased Johnsen scores. Training increased Sertoli cell counts and prevented their loss in TCP group. Leydig cells counts were increased in trained animals, but decreased in CP treated ones (TCP). We conclude that exercise have some protective effect on male reproductive tract submitted to a single dose of CP.

Objetivou-se investigar o efeito de exercício moderado crônico no trato reprodutivo masculino de ratos Wistar submetidos a uma dose única de ciclofosfamida (CP). Os animais foram submetidos ao exercício de natação por 21 dias ou mantidos em estado sedentário. Os grupos treinados (TCP) e sedentários (SCP) receberam uma única dose de CP (200 mg kg-1, ip). Os animais treinados (TCO) e sedentários (SCO) receberam PBS estéril. Os animais foram sacrificados após uma semana e os testículos, epidídimo e conteúdo da vesícula seminal foram pesados. As amostras foram embebidas em parafina e coradas com hematoxilina e eosina. Cinquenta túbulos seminíferos de cada animal foram analisados pelo escore Johnsen. A contagem média das células de Sertoli por túbulo e contagem das células de Leydig por área foram avaliadas. O tratamento CP prejudicou o ganho de peso corporal em animais treinados e sedentários. O fígado e o conteúdo da vesícula seminal foram reduzidos apenas no grupo SCO. Os animais SCP apresentaram menores escores de Johnsen, indicando uma toxicidade moderada sobre as células germinativas, enquanto os animais treinados (TCO e TCP) apresentaram escores de Johnsen mais altos. O treinamento aumentou a contagem de células de Sertoli e impediu a sua perda no grupo TCP. A contagem das células de Leydig foram aumentadas em animais treinados, mas reduzidas nos animais tratados com CP (TCP). Concluiu-se que o exercício tem algum efeito protetor sobre trato reprodutivo masculino de animais submetidos a uma dose única de CP.

Efeito do treinamento físico e da ingestão crônica de cafeína sobre o tecido ósseo de ratos jovens / Efecto del entrenamiento físico y la ingestión crónica de cafeína sobre El hueso de ratas jóvenes / Effect of exercise training and chronic caffeine intake on bone tissue of young rats

Foram avaliados os efeitos da ingestão crônica de cafeína e exercício de natação sobre o tecido ósseo. Ratos Wistar jovens (n = 32) alocados em quatro grupos: sedentário controle (SCO), sedentário + cafeína (SCAF), treinados (TCO) e treinados + cafeína (TCAF), receberam 1 mg/ml de cafeína em água durante 30 dias (SCAF e TCAF) e foram submetidos a 21 dias de natação em intensidade moderada (TCO e TCAF). A tíbia esquerda foi submetida a ensaio biomecânico para determinação do coeficiente de rigidez, limite de elasticidade e carga máxima. A área de tecido ósseo primário e espessura do disco epifisário foram avaliadas no fêmur. Não foram observadas alterações nas propriedades biomecânicas e na deposição de tecido ósseo primário. O grupo SCAF apresentou maior espessura no disco epifisário distal. Os resultados sugerem que o treinamento moderado de natação e a ingestão de cafeína não provocaram alterações morfológicas e biomecânicas do tecido ósseo.

Effects of swimming training and chronic caffeine intake on bone tissue of young rats were investigated. Young Wistar rats were allocated into 4 groups: sedentary control (SCO), sedentary + caffeine (SCAF), trained (TCO) and trained + caffeine (TCAF); they received 1 mg/ml of caffeine diluted in water for 30 days (SCAF and TCAF) and were submitted to swimming training of moderate intensity for 21 days (TCO and TCAF). The left tibia was subjected to the biomechanical test for determination of the coefficient of stiffness, yield and maximum load. The immature bone tissue area and thickness of growth plates were evaluated in the femur. No changes were observed in biomechanical properties and the area occupied by immature bone tissue. However, SCAF group presented greater thickness in distal growth plate. The results suggest that the moderate intensity swimming training and caffeine consumption were not able to promote changes in morphology and biomechanical properties of bone tissue.

Se evaluaram los efectos del consumo crónico de cafeína y la natación em el hueso. Ratas Wistar jóvenes (n=32) divididas en cuatro grupos: sedentarios control (SCO), sedentarios + cafeína (SCAF), entrenados (TCO) y entrenados + cafeína (TCAF), recibieron 1 mg/ml de cafeína en agua durante 30 días (SCAF e TCAF) e fueron sometidos 21 días de la natación moderada. La tibia izquierda se sometió a una prueba biomecánica para determinar la coeficiente de la rigidez, el limite de elasticidad y el punto de carga máxima. El area de hueso imaturo e de la zona de la placa de crescimiento proximal e distal se analizó em el fêmur. No se observaron cambios en las propiedades biomecánicas y el déposition de hueso inmaturo. Animales SCAF tenía más grueso de la placa de crescimiento distal. Los resultados sugieren que entrenamento moderalado de la natación y el cosumo crônico de cafeína no cambió la morfología y las propiedades biomecánicas del hueso.

Effects of chronic caffeine intake and low-intensity exercise on skeletal muscle of Wistar rats.

Caffeine can affect muscle cell physiology and the inflammatory response during exercise. The purpose of this study was to analyse muscle damage markers and inflammatory cell infiltration into the soleus muscle of sedentary and exercised animals submitted to chronic caffeine intake. Thirty-two male Wistar rats were divided into the following four groups (n = 8 per group): sedentary control (SCO); sedentary + caffeine (SCAF); trained control (TCO); and trained + caffeine (TCAF). The animals were housed in individual cages and received tap water or caffeine (1 mg ml(-1)); they were maintained at rest or submitted to swimming for up to 40 min day(-1) with a 4% load, five times per week for 30 days. Blood samples were collected for analysis of serum lactate, creatine kinase and calcium. The right soleus muscle and the epididymal fat depot were weighed, and the muscle was submitted to histological analysis. Training and caffeine did not change body or muscle weight, food and liquid intake or serum calcium levels among groups. Decreased fat tissue (P < 0.05) was observed in the SCAF (4.05 ± 1.03 g), TCO (4.14 ± 0.78 g) and TCAF groups (4.02 ± 1.02 g) compared with the SCO group (5.31 ± 1.06 g). Serum creatine kinase activity was significantly reduced in the SCAF (787.3 ± 230.3 U l(-1)), TCO (775.3 ± 232.3 U l(-1)) and TCAF groups (379.5 ± 110.5 U l(-1)) compared with the SCO group (1610.2 ± 276.5 U l(-1)). Few damaged muscle fibres (P < 0.05) were found in SCAF (16.7 ± 12.8%) and TCAF groups (17.3 ± 11.7%) compared with the SCO group (53.6 ± 13.9%). The SCAF group presented fewer fields with inflammatory cells (7.6 ± 8.7 fields) compared with the SCO group (123 ± 146 fields). The results suggest that the chronic intake of caffeine, as well as chronic low-intensity exercise, decreased muscle damage and inflammatory infiltration into skeletal muscle.

Isolated and combined effects of aerobic and strength exercise on post-exercise blood pressure and cardiac vagal reactivation in normotensive men.

The purpose of this study was to examine blood pressure (BP), heart rate (HR), and cardiac vagal reactivation (VR) after an aerobic training session (ATS), a strength training session (STS), and a combined aerobic and strength training session (ASTS) in normotensive men. Eleven healthy men (age 26.8 ± 2.9 years, body mass index 24.3 ± 1.6 kg·m) with at least 6 months of strength and aerobic training experience performed an STS, an ATS, and an ASTS in a counterbalanced crossover design. Blood pressure and HR were measured at rest and at 15-minute intervals post-training for 1 hour. Vagal reactivation was measured during the first minute immediately post-exercise. After STS and ASTS, systolic BP (SBP) and mean arterial BP (MAP) remained significantly lower than at rest at all time intervals (p < 0.05). After ATS, SBP was significantly lower than at rest at 30 minutes and beyond (p < 0.01); however, no significant differences were observed for MAP. Post-training HR remained high after STS and ASTS at all intervals (p < 0.01). However, after ATS, the HR remained high only at the 15-minute post-exercise interval (p < 0.01). Vagal reactivation was significantly less pronounced after the first 30 seconds post-exercise (p < 0.01) in ASTS (531.3 ± 329.6 seconds) than in ATS (220.7 ± 88.5 seconds) and in STS (317.6 ± 158.5 seconds). The delta of the HR decrease at 60 seconds post-exercise was greater (p < 0.00) in ATS (33.4 ± 12.7 b·min) than in STS (14.1 ± 7.2 b·min) and in ASTS (11.4 ± 7.1 b·min). In conclusion, post-exercise BP reduction was independent of the type of exercise; however, HR remained significantly greater after combination of strength and aerobic exercise, implying a reduction in cardiac VR after this type of training. Therefore, strength and conditioning professionals may prescribe aerobic, strength, or a combination of aerobic and strength exercise to assist individuals concerned with BP control, thus allowing for variety in training while similarly impacting post-exercise SBP regardless of desired exercise modality.